The present invention relates to rigid coaxial transmission lines and more particularly to such a line having low VSWR characteristics over a substantial band of frequencies.
For various high power applications, e.g., UHF television transmission, it is conventional to couple RF power between the transmitter and the antenna through a rigid coaxial transmission line. Further, in some applications, the transmitter may be located a substantial distance from the antenna so that the transmission line is necessarily made up of multiple sections. Conventionally, such multi-section runs are made up of sections which are essentially all of the same length since this simplifies design and manufacturing. To prevent accumulating interference effects, the length of each section is normally selected so as to not be a multiple of a half wavelength of the frequency corresponding to the channel allocation for the particular T.V. station. In some instances however, an antenna may be operated at a variety of frequencies within a substantial band and this prior art technique may be ineffective in preventing reflections accumulating to an unacceptable voltage standing wave ratio (VSWR).
Among the several objects of the present invention may be noted the provision of a multi-section run of RF transmission line having low VSWR characteristics over a substantial band of frequencies; the provision of such a transmission line which can be constructed in the form of a rigid coaxial transmission line; the provision of such a transmission line which can be constructed in coaxial sections having outer conductors which are connected together at flange joints; the provision of such a transmission line which is highly reliable and which is of relatively simple and inexpensive constructions. Other objects and features will be in part apparent and in part pointed out hereinafter.